INVESTIGATORS ARE examining the formwork system used at a Las Vegas esidential tower block which collapsed during construction.
The floor slab on the second floor of the 45-storey Turnberry Place building collapsed at 9am on Monday 31 October, injuring seven people. The Occupational Safety & Health Administration (OSHA) has closed the site while it investigates the cause.
It is understood that construction of the tower was being undertaken using a atively new technique known as column-hung forming.
This system eliminates the need for temporary propping beneath the floor slab and speeds up construction by as much as 30%.
Floors are created by first pouring the columns on top of the floor slab below. Jacks are fixed to the columns as soon as they have developed enough strength. Large sections of timber faced formwork backed by robust steelwork are craned in between the columns and placed on top of the jacks.
The formwork is levelled, then reinforcement placed before the concrete is poured.
Once the concrete has gained enough strength the jacks are loosened and the formwork can be slid out.